Patent GB-264369-A (GB)
Title: Improvements in color cinematography
IPC: G03B33/00
Filed: 1926-04-12
Abstract: 264,369. Technicolor Motion Picture Corporation, and Ball, J. A. April 12, 1926. Colour photography; printing-apparatus.-Complementary colour-record kinematograph films which are subsequently to be dyed for use as matrices in dye-printing processes, or are to be cemented together in superimposition to form a composite film in natural colours, are produced by feeding blank films along angular paths which are adjacent along one side of the angles, and forming the images on the respective films on the other side of the angles as by printing from colour-record negatives. The images may be printed through the film supports if clear gelatine relief pictures are to be produced, as in Specification 188,329; and the films may be cemented together back to back when they are brought into adjacence, for subsequent development as in Specification 209,404. In printing, the intensities of the printing lights may be varied to compensate for variations in density throughout the length of either film, or to regulate the relative exposures required by the two films to yield a balanced colour picture. The film gates at which the two images are printed are preferably adjacent, and the beams from the printing lights preferably cross before reaching their respective gates, so that a single shutter may be located at or near the position where they :cross. As shown, colour-record images in alternating sequence on a negative film N, Fig. 1, are printed, one series on a positive film P, and the other on a positive film Pl. The negative film, after passing through tensioning-means a, is fed in succession through both gates G, G<1>, between which is situated an eccentrically-mounted roller 7 whereby the images may be registered with the gates. The positive film P, after passing through tensioning-means a<1>, is fed through the gate G only, whence it bends at right angles over a roller 1, and passes beneath a sliding perforator 2 to a roller 3, sprockets L, n<1>, and a take-up reel. The positive P<1> after passing through tensioning means all is fed through the gate G' only, whence it bends at right angles over a roller 4, and passes, in parallel relation to the film P, beneath a sliding perforator 5 to a roller 6 sprockets J, o and a takeup reel. The images on the negative film are alternately erect and inverted in the direction of the length of the film as in Specification 194,971, [Class 97 (i). Optical systems &c.]. in order that; the printed positive images may register when the positive films are brought into juxtaposition after leaving the gates. The moving parts are all driven from a motor-driven pulley through toothed wheel gear trains. The sprocket F for the negative film and the sprockets J, L for the positive films are driven intermittently through Geneva movements having the usual fly-wheels. A clutch is provided in the driving mechanism to permit the negative film to be run through without unthreading when it is desired to omit any portion of it. The pressure plate Q, Fig. 7, in the film gate G and a similar plate in the gate G<1> are actuated by a link 48 turning on a shaft 47 and having an extension 49 carrying a roller 50 working in a cam groove 44 on a shaft 43 driven from the main pulley. Registering pins 51 sliding in guides 52 opposite both gates are actuated by an arm 53 turning on a shaft 54 and having an extension 55 carrying a roller 56 working in a cam groove 45 on the shaft 43. The shaft 43 also carries a third cam groove 46 which actuates mechanism for displacing the positive film rollers 3, 6 and also a roller 63, Fig. 1, bearing against the negative film, to release the tension on the films just prior to the advance of the registering pins 51 into the sprocket holes of the films. Two printing lights, one for each gate, are located in a housing (not shown) to the left of Fig. 1, and the beams therefrom are directed to the gates G, G<1> through telescoping casings 64, 65. In the casing 64, and situated immediately in advance of a rotating shutter is a partition 66 having a central opening 67 through which the light beams are caused to pass, so that they cross at the opening. By this device, one shutter is made to serve for both beams. Notches are made in the negative film at the points where variation of (1) the average intensity of the two printing-lights and (2) their relative intensities is necessary. These notches actuate a lever switch 80, Fig. 12. to close momentarily the circuit of an electro-magnetic escapement device 79, 78, thereby causing a contact bar 72 which is fast with the escapement rod to fall through one step. The bar 72 engages, two at a time, studs 74 which are previously set according to the desired changes of light in a series of bars 71 connected to taps from two rheostats 69, 70. The circuit from the mains 68 passes in parallel through the lamps U, V to the ends of the rheostat 70 and through this from each end to the right-hand stud 74 under the bar 72; thence it passes along the bar 72 to the left-hand stud, and back to the mains through the active part of the rheostat 69. The left-hand studs are set to vary the average intensities of the two lights, and the right-hand studs to vary their relative intensities. The printing gates G, G<1> may be so spaced apart as to print simultaneously either the two adjacent images of the negative film which together form one picture, or two non-adjacent images belonging to different picture-sets, for example, images separated by twointervening images. In the latter case, if it is desired that the positive films shall register when they pass from the gates into parallel juxtaposition, one of the films is threaded as it leaves the film gate over three rollers situated at the corners of a triangle, instead of over the single roller 1. Specification 238.445 also is referred to.